AQA A Level Chemistry
AQA A Level Chemistry 3.2.2 Group 2, the Alkaline Earth Metals Exam Questions
Free AQA A Level Chemistry exam questions for 3.2.2 Group 2, the Alkaline Earth Metals, with a mark scheme for every pack. Covers Group 2 trends, reactions with water, solubility of hydroxides and sulfates, uses of compounds and the sulfate test.
3.2.2 Group 2, the Alkaline Earth Metals exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About AQA A Level Chemistry 3.2.2 Group 2, the Alkaline Earth Metals
Group 2 is an AS inorganic topic on the AQA A Level course. You need the trends down the group from magnesium to barium in atomic radius, first ionisation energy, melting point and reactivity, the reactions of the metals with water, and the solubility trends of the hydroxides and sulfates. You also learn uses of Group 2 compounds, the extraction of titanium using magnesium, removal of sulfur dioxide from flue gases with calcium oxide or carbonate, and the barium chloride test for sulfate ions. Required practical 4 covers test-tube reactions to identify ions. Examiners like equations, observations and explanations of trends using atomic structure.
What you need to know
- Physical trends Down Group 2 atomic radius increases, first ionisation energy decreases because of greater distance and shielding, and melting point generally decreases because the metallic bonding gets weaker as the ions get larger.
- Reactions with water Reactivity increases down the group. Magnesium reacts very slowly with cold water but burns in steam: Mg + H2O → MgO + H2. Calcium, strontium and barium react with water to form hydroxides and hydrogen, e.g. Ca + 2H2O → Ca(OH)2 + H2.
- Solubility trends Hydroxides become more soluble down the group; Mg(OH)2 is sparingly soluble. Sulfates become less soluble down the group; BaSO4 is insoluble.
- Uses Mg(OH)2 is used in medicine as an antacid, Ca(OH)2 is used to neutralise acidic soils, BaSO4 is used in barium meals for X-rays, and CaO or CaCO3 removes SO2 from flue gases. Magnesium extracts titanium: TiCl4 + 2Mg → Ti + 2MgCl2.
- Sulfate test Add dilute hydrochloric or nitric acid, then barium chloride solution. A white precipitate of BaSO4 shows sulfate ions. The acid removes carbonate ions, which would also give a white precipitate.
Common mistakes in 3.2.2 Group 2, the Alkaline Earth Metals
- Writing magnesium hydroxide as the product of magnesium and steam. With steam the products are magnesium oxide and hydrogen.
- Mixing up the solubility trends. Hydroxides get more soluble down the group; sulfates get less soluble.
- Acidifying with sulfuric acid in the sulfate test. This adds sulfate ions; use hydrochloric or nitric acid.
- Explaining the falling ionisation energy only by more protons. The increased distance and shielding outweigh the greater nuclear charge.
- Saying barium sulfate is safe for a barium meal because barium is harmless. Soluble barium compounds are toxic; BaSO4 is safe because it is insoluble.
Try three 3.2.2 Group 2, the Alkaline Earth Metals exam-style questions
1. Write an equation for the reaction of magnesium with steam. (1 mark)
Show the mark scheme answer
Mg + H2O → MgO + H2.
2. Describe the test for sulfate ions and explain why the solution is acidified first. (3 marks)
Show the mark scheme answer
Add dilute hydrochloric acid then barium chloride solution; a white precipitate forms if sulfate is present; the acid reacts with carbonate ions, which would otherwise also give a white precipitate.
3. Write an equation for the extraction of titanium from titanium(IV) chloride using magnesium, and give the role of magnesium. (2 marks)
Show the mark scheme answer
TiCl4 + 2Mg → Ti + 2MgCl2; magnesium is the reducing agent.
3.2.2 Group 2, the Alkaline Earth Metals FAQs
What does AQA A Level Chemistry 3.2.2 Group 2 cover?
It covers trends in Group 2 properties, reactions of the metals with water, solubility of hydroxides and sulfates, uses of Group 2 compounds and the test for sulfate ions.
Which paper is 3.2.2 Group 2 examined in?
It is examined in Paper 1, and Paper 3 can also test it, often through Required practical 4.
Which equations do I need to learn for Group 2?
Learn the reactions of the metals with water (including magnesium with steam), the extraction of titanium using magnesium, the removal of SO2 with CaO or CaCO3, and the ionic equation Ba2+ + SO4 2- → BaSO4.
